The objective of this thesis was to investigate the influence of lactic acid fermentation on the nutritional value of microalgae Arthrospira platensis and Chlorella vulgaris. The nutritional composition of microalgae was determined with the chemical analyses before and after lactic acid fermentation (LAF), which included determination of total fat, fatty acid composition, protein, ash, dietary fiber and certain elements (Ca, Mg, Fe, Na and K). Total fat was determined by Weibull- Stoldt method, fatty acids by gas chromatography, proteins by Kjeldahl method and ash by ashing in a furnace at 550 ºC. The dietary fibre content was determined by enzyime-gravimetric method, and elements according to AOAC 999.11 method. We have determined only minor changes in the nutritional value of both microalgae after LAF, energy value in C. vulgaris decreased by almost 1,3 % or 18 kJ/100g, while increase was negligible in A.platensis (0,5 % or 8 kJ/100g). In both microalgae, the content of fat decreased after LAF (for 6 % or 0,37 g/100 g of dry matter in A. platensis and 1,9 % or 0,15 g/100 g of dry matter in C. vulgaris). Also, the proportions of certain fatty acid and contents of elements were different after LAF. There were represented fewer fatty acids after LAF (palmitic acid accounted for the largest portion). In A. platensis the proportion of elements decreased after LAF but in C. vulgaris increased after LAF. Our analyses suggest LAF affected the protein content. The content of non-protein nitrogen increased and of protein nitrogen decreased during LAF. Both microalgae differed significantly in the content of protein, A. platensis contained more proteins. LAF provoked a decrease of soluble fiber, while the insoluble fiber content increased in both A. platensis and C. vulgaris.
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